The reading of electrical energy, water flow, and gas usage has historically been accomplished with human meter readers who came on-site and manually documented meter readings. Over time, this manual meter reading methodology has been enhanced with walk by or drive by reading systems that use radio communications to and from a mobile collector device in a vehicle. Recently, there has been a concerted effort to accomplish meter reading using fixed communication networks that allow data to flow from the meter to a host computer system without human intervention.
Fixed communication networks can operate using wire line or radio technology. For example, distribution line carrier systems are wire-based and use the utility lines themselves for communications. Radio technology has tended to be preferred due to higher data rates and independence from the distribution network. Radio technology in the 902-928 MHz frequency range can operate without a Federal Communications Commission (FCC) license by restricting power output and by spreading the transmitted energy over a large portion of the available bandwidth.
Some conventional utility meter reading communication networks use multiple repeaters. In some such networks, a head end computer system keeps track of the distribution network configuration and configures the repeaters to work within that distribution network. Such networks work well as long as the power line network do not change configuration and the propagation characteristics of the network remain constant. Alternate routing schemes can be built into the hardware so that the master computer can select different paths to achieve end device communication. One drawback of this type of network is that the network must be managed from the master computer. As the number of end points grows, there is a need to move intelligence further into the network and have routing decisions made in the remote hardware.
Automated systems, such as Automatic Meter Reading (AMR) and Advanced Metering Infrastructure (AMI) systems, exist for collecting data from meters that measure usage of resources, such as gas, water and electricity. Such systems may employ a number of different infrastructures for collecting this meter data from the meters. For example, some automated systems obtain data from the meters using a fixed wireless network that includes, for example, a central node, e.g., a collection device, in communication with a number of endpoint nodes (e.g., meter reading devices (MRDs) connected to meters). At the endpoint nodes, the wireless communications circuitry may be incorporated into the meters themselves, such that each endpoint node in the wireless network comprises a meter connected to an MRD that has wireless communication circuitry that enables the MRD to transmit the meter data of the meter to which it is connected. The wireless communication circuitry may include a transponder that is uniquely identified by a transponder serial number. The endpoint nodes may either transmit their meter data directly to the central node, or indirectly though one or more intermediate bi-directional nodes which serve as repeaters for the meter data of the transmitting node.
Some networks may employ a mesh networking architecture. In such networks, known as “mesh networks,” endpoint nodes are connected to one another through wireless communication links such that each endpoint node has a wireless communication path to the central node. One characteristic of mesh networks is that the component nodes can all connect to one another via one or more “hops.” Due to this characteristic, mesh networks can continue to operate even if a node or a connection breaks down. Accordingly, mesh networks are self-configuring and self-healing, significantly reducing installation and maintenance efforts.
Within these smart mesh networks, communications are achieved from a central collector through repeaters to endpoints, and the number of repeaters in a chain can be quite large. There are two different methods for extracting data from mesh networks: polling and bubble up. In a polling approach, the route from a collector to an endpoint is established and data is pulled from the endpoint by sending a unicast packet to the endpoint and back. In a bubble up approach, the data may be originated at the endpoint based on a schedule or a prior instruction, and the route to the collector or gateway can be dynamically determined.
For high priority exception messages, such as “last gasp” outage notifications or for messages from a simple device that can only function as a transmitter, messages may be broadcast into the network. The advantage of such a broadcast is any device in the network that receives the message can forward it to its registered collector. This allows a given message to be forwarded via multiple communication paths to one or more collectors. One disadvantage, however, is that data is stored in multiple devices, and the redundant data requires multiple communications between the device and the collector when a given data message only needs to be transferred one time. Network inefficiencies may occur as a result.